This invention relates generally to axle assemblies and, more particularly, to the fastening of the axle shaft to the hub of a drive axle assembly.
Drive axle assemblies become more and more complex due to the greater and greater load demands placed on them. To keep pace with the ever increasing performance demands on drive axles, improvements have been made in the various lubricants for the various operational parts of the drive axle. One area of criticality is the roller bearings which rotatably support the driven hubs located at the ends of the drive axle assembly. These roller bearings see tremendous loads, including severe mechanical shock loading. Loss of lubrication to these roller bearings could result in substantial damage to the drive axle assembly and could also result in a serious accident should the driver lose control of the vehicle due to a seized wheel bearing. The lubricant for the roller bearings is typically contained within a lubricant reservoir disposed at the ends of the axle assemblies. Another area of criticality is the differential mechanism which splits the power of the drive train to the various drive wheels associated with the vehicle. As with the wheel bearings, the differential mechanisms are exposed to greater and greater operational loading and, therefore, its parts must be continuously and effectively lubricated. The lubricant reservoir for both of these operational mechanisms is defined by an inner seal typically between the wheel hub and the axle housing and a seal between the wheel hub and the axle shaft head. With respect to the latter seal, the prior art included a paper gasket or other similar gasket between the axle head and the hub. Additionally, the prior art included certain forms of dowels and the like to further secure the axle shaft to the hub and increase the pressure exerted on the gasket therebetween. However, because of the inherent resiliency or give of the paper gasket or the like, certain relative movement is encountered between the axle head and the axle shaft of the hub. This relative movement results in a seal breakdown and deterioration of the studs (and/or tapered dowels) fastening the axle shaft head to the hub resulting ultimately in the failure of the seal and, more importantly, of the fastening studs which could cause the loss of the wheel.